1. Field of the Invention
The present invention relates to a telecommunications system which allows remote mobile terminal equipment to call and interchange information with each other via a public switched telephone network, paging station, radio link controller, etc. The present invention is also concerned with terminal equipment applicable to such a telecommunications system, and a method of communicating with the mobile terminal equipment through a public switched network.
2. Description of the Background Art
In one of conventional mobile telecommunications systems, a personal computer or similar information transmitting center system calls radio terminal equipment having a receiver capability only via a public switched telephone network and a radio paging station, and then sends desired information to the terminal equipment. The personal computer, for example, is installed in an office or similar facility while the terminal equipment is carried by a staffer belonging to the office. The staffer, therefore, can receive information from the office at any place outside the office. However, the problem with this system is that only the fixed center can send information, whereas such terminal equipment located outside the office cannot send information to another terminal equipment also located outside the office. In addition, only the fixed center can transmit call indication information.
Another type of conventional mobile telecommunications system allows two remote radio terminal equipment, or mobile stations, to communicate with each other via a radio base station. With this kind of system, a radio base station is connected to a public switched telephone network through a central office. A mobile station intending to send information to a remote mobile station transmits an originating call signal. In response, the radio base station designates a particular communication channel and then checks the mobile station. When the communication channel is set up, the calling mobile station sends a dial number designating a mobile station to be called. The central office sends a calling signal to the called mobile station on the basis of the dial number. Then, the called station returns an answer signal, and the base station in turn selects a communication channel. In this condition, the remote, two mobile stations can start communicating with each other over the designated communication channel. However, when a person expected to handle the called mobile station is absent or has suppressed the output of ringing, information cannot be delivered from the calling mobile station to that called mobile station despite the ringing from the calling station. Specifically, this type of conventional telecommunications system does not take account of the fact that when a calling person sends information to a called mobile station, a called person may have left the called mobile station or intentionally switched off the mobile station, or may not answer the call for one reason or another.